trigsimp() will convert the sin to cos. To remove the negative and
square, you'll have to use expand_log(force=True), which gives a
complex constant (which can be ignored, since this is an integral).

It would definitely be better if integrate at least gave log(1 -
sin(x)**2) so that the result is real.

Aaron Meurer

On Fri, Feb 19, 2016 at 8:07 AM, Carsten Knoll <[email protected]> wrote:
> I want to calculate the antiderivative for tan(x)
>
> In [4]: x = sp.Symbol('x', real=True)
>
> In [5]: sp.integrate(sp.tan(x), x)
> Out[5]: -log(sin(x)**2 - 1)/2
>
>
> This result is technically correct, but I would (for didactic purposes)
> prefer something like
>
> -log(cos(x)).
>
> How can I achieve this?
>
> Thanks.
> Carsten.
>
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